Methods for the detection and characterization of specific nucleic acid sequences and sequence variations have been used to detect the presence of viral or bacterial nucleic acid sequences indicative of an infection, to detect the presence of variants or alleles of genes associated with disease and cancers. These methods also find application in the identification of sources of nucleic acids, as for forensic analysis or for paternity determinations.
Various methods are known to the art that may be used to detect and characterize specific nucleic acid sequences and sequence variants. Nonetheless, with the completion of the nucleic acid sequencing of the human genome, as well as the genomes of numerous pathogenic organisms, the demand for fast, reliable, cost-effective and user-friendly tests for the detection of specific nucleic acid sequences continues to grow. Importantly, these tests must be able to create a detectable signal from samples that contain very few copies of the sequence of interest. The following discussion examines two levels of nucleic acid detection assays currently in use: I. Signal Amplification Technology for detection of rare sequences; and II. Direct Detection Technology for quantitative detection of sequences.